Opinion: Could giving peanuts to infants decrease allergy incidence?

Animal research has shown that if a food is eaten and then absorbed through the intestines, babies have a good chance of being able to eat the particular food. However, if early in life, the food is absorbed through the skin by dust particles in the air or by rubbing creams that have components like peanut or almond, an allergy may develop.

Parents today are frequently faced with a major predicament. So many children have food allergies. Every classroom has someone whose picture is on the wall because of a potentially life-threatening allergy to a food such as peanut.

What can I as a parent do to prevent this? For many years, the answer was virtually nothing. There was little understanding about why the number of children with food allergies was increasing, no idea about how to prevent them, and few options for treatment beyond avoiding the foods. In fact, in the late ’90s, an attempt was made to prevent allergies by delaying the introduction of solids to infants until after 6 months, and delaying foods that were more associated with allergy, such as milk and eggs, until after 12 months. Recommendations for eating peanuts and tree nuts, for children at high risk of allergies, suggested only starting these foods after 3 years of age. However, our food allergy epidemic continued to grow. In most studies that evaluated if these strategies really helped, the results were not favourable for avoidance. In fact, in 2008 the American Academy of Pediatrics and its European counterpart cancelled the recommendations for delaying solids and other allergenic foods. This really left most doctors and families very confused. New strategies for feeding children with a high risk of allergy were sorely needed.

Animal research into how and why tolerance (ability to eat) to foods occurs shed a bit of light on this problem. If a food is eaten and then absorbed through the intestines, babies have a good chance of being able to eat the particular food. However, if early in life, the food is absorbed through the skin by dust particles in the air or by rubbing creams that have components like peanut or almond, an allergy may develop. In mice, rubbing peanut on inflamed skin causes allergy while feeding the mice the same food does not. Children at high risk for food allergies frequently have eczema, dry, irritated, cracked skin and food allergy is very common in these children. The second interesting observation in people was that in countries like Israel where children ate peanuts early in the first year of life, peanut allergy was very uncommon compared to countries like Great Britain and the U.S. where parents typically waited until after 12 months or even 3 years before introducing peanuts into their children’s diets.

Researchers in Great Britain, under the direction of Professor Gideon Lack, decided to address this problem head on. They started the Learning Early About Peanut Allergy study (LEAP). They researched over 600 children aged 4-11 months who had either eczema or egg allergy, and in a random fashion, instructed half to continue the normal British recommendation and avoid eating peanuts until 5 years of age. The other half was instructed to eat a set amount of peanut three times a week. All children were tested for peanut allergy before and both groups had subjects who showed signs of early peanut allergy. In fact, there were children who had strong positive skin tests to peanuts before starting; they were not included in the treatment groups. After 5 years, all children had blood and skin tests to see if they were potentially allergic to peanuts, and then were given peanuts orally in the hospital in a controlled setting. The results were very exciting. Giving children peanuts to eat regularly from before their first birthday decreased the chance of having peanut allergy at age 5 by more than 80 per cent. These results are a good indication that peanut avoidance does not prevent peanut allergy, and the earlier it is given to babies, the more likely they can avoid this problem.

Can this strategy prevent peanut allergy in all children? No treatment or prevention strategy is perfect. Even in the LEAP study, some children had signs of peanut allergy before they were able to be put into a treatment group. It may be dangerous to start these children on peanut early. A small number developed symptoms of peanut allergy while eating peanuts regularly. In general, if a child does not have eczema or other food allergies by 4-6 months, it is probably fine to start eating peanuts. If a child does have bad eczema or another food allergy like egg allergy, then the family should consult their doctor who may refer them to an allergy specialist.

Can this strategy be used to decrease the chance of allergies to other food? This is a good question, but it is too early to answer. Avoidance for many months or years did not provide good protection. It is certainly safe to follow the new recommendations about starting solids in babies after 4-6 months of life and the data in the LEAP study and others suggest that a varied diet with nuts, fish and other foods associated with allergies could provide protection. However, these studies have not been done yet. We know that there are many cultures, like in Scandinavia, where fish is given early in life and the incidence of fish allergy is very low. Another study from Israel showed that babies who received milk formula in the first week of life had the lowest chance of developing milk allergy later. These studies suggest that parents of children at high risk for food allergies may be able to prevent other allergies in a similar manner. Time will tell if this is true.

Should parents take the LEAP and feed their babies peanut? It certainly appears that there may be a simple and effective strategy that can lower the number of kids with pictures on the wall at school.

Bruce Mazer is division head of Allergy and Immunology at the Montreal Children’s Hospital.

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